The present invention relates to an electrophotographic copying machine and, more particularly, to a device for detecting the size of a copy document on a document table for an electrophotographic copying machine.
An electrophotographic copying machine produces an electrostatic latent image on an optical-sensitive member. The latent image corresponds to an image on a copy document such as a manuscript or book to be copied. Toner particles are electrically adhered to the latent image, so that the latent image becomes visible to form a toner image.
The toner image is transferred onto a copy paper via a transference charger. Depending upon the size of the copy document, the size of the copy paper should be selected. To properly select the copy paper size, some sensors must be provided adjacent the document table for detecting the size of the copy document.
Conventionally, each of the sensors comprises a light receiving element. When the copy document is positioned on the document table, the copy document interrupts surrounding light from being incident upon the light receiving element. The copying machine is responsive to the output from the light receiving element for detecting the size of the copy document.
Since each of these sensors is directed to detect individual sizes of a plurality of copy documents, error detection can not be avoided, in particular, when the copying machine is disposed in the dark.
Therefore, it is desired to provide an improved detection device for detecting the sizes of the copy documents on the document table for preventing any error in detection.